Biomass Production System Hardware Performance

Goins

et al. 2005

The concept of using higher plants to maintain a sustainable life support system for humans during long-duration space missions is dependent upon photosynthesis. The effects of extended exposure to microgravity on the development and functioning of photosynthesis at the leaf and stand levels were examined onboard the International Space Station (ISS). The PESTO (Photosynthesis Experiment Systems Testing and Operations) experiment was the first long-term replicated test to obtain direct measurements of canopy photosynthesis from space under well-controlled conditions. The PESTO experiment consisted of a series of 21-24 day growth cycles of Triticum aestivum L. cv. USU Apogee onboard ISS. Single leaf measurements showed no differences in photosynthetic activity at the moderate (up to 600 micromol m(-2) s(-1)) light levels, but reductions in whole chain electron transport, PSII, and PSI activities were measured under saturating light (>2,000 micromol m(-2) s(-1)) and CO(2) (4000 micromol mol(-1)) conditions in the microgravity-grown plants. Canopy level photosynthetic rates of plants developing in microgravity at approximately 280 micromol m(-2) s(-1) were not different from ground controls. The wheat canopy had apparently adapted to the microgravity environment since the CO(2) compensation (121 vs. 118 micromol mol(-1)) and PPF compensation (85 vs. 81 micromol m(-2) s(-1)) of the flight and ground treatments were similar. The reduction in whole chain electron transport (13%), PSII (13%), and PSI (16%) activities observed under saturating light conditions suggests that microgravity-induced responses at the canopy level may occur at higher PPF intensity.

Section: Discussionmentioning

confidence: 95%

“…The PESTO experiment was conducted in PGCs 1-3 of the BPS. The fourth PGC was planted with B. rapa as part of a separate hardware validation test (Morrow and Crabb 2000; Iverson et al 2003). …”

Section: Spaceflight Hardwarementioning

confidence: 99%

Microgravity effects on thylakoid, single leaf, and whole canopy photosynthesis of dwarf wheat

Goins

et al. 2005

“…The PESTO experiment was conducted in PGCs 1-3 of the BPS. The fourth PGC was planted with Brassica rapa as part of a separate hardware validation test (Morrow and Crabb 2000;Iverson et al 2003). …”

Section: Spacexight Hardwarementioning

confidence: 99%

“…The plants were grown in Xight hardware that was optimized to minimized the most glaring of the "spaceXight" factors, such as lack of convective currents, inadequate CO 2 , temperature control, relative humidity, soil moisture and ethylene control (Morrow and Crabb 2000;Iverson et al 2003) that confounded interpretation of early spaceXight experiments .…”

Section: Introductionmentioning

confidence: 99%

Microgravity effects on leaf morphology, cell structure, carbon metabolism and mRNA expression of dwarf wheat

Hatfield

et al. 2006

The use of higher plants as the basis for a biological life support system that regenerates the atmosphere, purifies water, and produces food has been proposed for long duration space missions. The objective of these experiments was to determine what effects microgravity (microg) had on chloroplast development, carbohydrate metabolism and gene expression in developing leaves of Triticum aestivum L. cv. USU Apogee. Gravity naive wheat plants were sampled from a series of seven 21-day experiments conducted during Increment IV of the International Space Station. These samples were fixed in either 3% glutaraldehyde or RNAlater or frozen at -25 degrees C for subsequent analysis. In addition, leaf samples were collected from 24- and 14-day-old plants during the mission that were returned to Earth for analysis. Plants grown under identical light, temperature, relative humidity, photoperiod, CO(2), and planting density were used as ground controls. At the morphological level, there was little difference in the development of cells of wheat under microg conditions. Leaves developed in mug have thinner cross-sectional area than the 1g grown plants. Ultrastructurally, the chloroplasts of microg grown plants were more ovoid than those developed at 1g, and the thylakoid membranes had a trend to greater packing density. No differences were observed in the starch, soluble sugar, or lignin content of the leaves grown in microg or 1g conditions. Furthermore, no differences in gene expression were detected leaf samples collected at microg from 24-day-old leaves, suggesting that the spaceflight environment had minimal impact on wheat metabolism.

“…PESTO was conducted in PGCs 1-3 of the BPS. The 4th PGC was planted with Brassicca rapa as part of a separate hardware validation test (Morrow et al 2001;Iverson et al 2003). …”

Section: Spaceflight Hardwarementioning

confidence: 99%

Microgravity does not alter plant stand gas exchange of wheat at moderate light levels and saturating CO2 concentration

Chapman

2005

Plant stand gas exchange was measured nondestructively in microgravity during the Photosynthesis Experiment Subsystem Testing and Operations experiment conducted onboard the International Space Station. Rates of evapotranspiration and photosynthesis measured in space were compared with ground controls to determine if microgravity directly affects whole-stand gas exchange of Triticum aestivum. During six 21-day experiment cycles, evapotranspiration was determined continuously from water addition rates to the nutrient delivery system, and photosynthesis was determined from the amount of CO2 added to maintain the chamber CO2 concentration setpoint. Plant stand evapotranspiration, net photosynthesis, and water use efficiency were not altered by microgravity. Although leaf area was significantly reduced in microgravity-grown plants compared to ground control plants, leaf area distribution was not affected enough to cause significant differences in the amounts of light absorbed by the flight and ground control plant stands. Microgravity also did not affect the response of evapotranspiration to changes in chamber vapor pressure difference of 12-day-old wheat plant stands. These results suggest that gravity naïve plants grown at moderate light levels (300 micromol m(-2) s(-1)) behave the same as ground control plants. This implies that future plant-based regenerative life support systems can be sized using 1 g data because water purification and food production rates operate at nearly the same rates as in 1 g at moderate light levels. However, it remains to be verified whether the present results are reproducible in plants grown under stronger light levels.